Novel bleaching compositions and use thereof

ABSTRACT

Stability of perphthalic acids is improved by alkali metal or alkaline earth metal salts of an acid with an ionization constant at 25* C. for the first hydrogen of at least 1 X 10 3. The mixtures can be protectively coated with water removable coatings. Magnesium salts enhance the bleaching effect of diperisophthalic acid.

United States Patent Nielsen 1 Feb. 1, 1972 [54] NOVEL BLEACHING COMPOSITIONS [58] Field of Search ..252/l00, 186', 8/1 I 1; 260/502 AND USE THEREOF [56] References Cited [72] Inventor: Donald R. Nielsen, Corpus Christi, Tex.

FORE N PATENTS OR APPLICATIONS [73] Assignee: PPG Industries, lnc., Pittsburgh, Pa. [2 F d J l 23 19 560,389 9/1957 Belgium ..260/502 R 1 e z u y [21] Appl- No; 859,521 Primary Examiner-Mayer Weinblatt Related u.s. Application Data [571 ABSTRACT [63] Continuation of No 584 969 Oct 7 1966 aban Stability of perphthalic acids is improved by alkali metal or aldoned continuaflndnl of i 323 kaline earth metal salts of an acid with an ionization constant Se I963 abandohe at 25 C. for the first hydrogen of at least IXIQTF. The mixp tures can be protectively coated with water removable coatings. Magnesium salts enhance the bleaching effect of [52] US. Cl ..252/l00, 8/1 1 l, 22562O//l58O62, diperisophthalic acid [51 1 Int. Cl. ..Cl1d 7/54 7 Claims, No Drawings NOVEL BLEACHING COMPOSITIONS AND USE THEREOF This application is a continuation-in-part of application Ser. No. 308,323, filed Sept. 12, 1963 now abandoned. This application is a continuation of application Ser. No. 584,969, filed Oct. 7, 1966 and now abandoned.

This invention is directed to the stabilization of perphthalic acids, such as the peracid of phthalic, terephthalic or isophthalic acids, and the halogenated (particularly the fluorinated or chlorinated) perphthalic acids, and their preparation and use as bleaching agents especially for the bleaching of textiles. These acids are capable of liberating active oxygen for bleaching and various oxidizing reactions. As a general rule, these peracids are characterized by a certain degree of instability and gradually decompose, losing their active oxygen content as they are allowed to stand. Heretofore, addition of other agents to these materials has resulted in little, if any, improvement in stability.

In accordance with this invention, it has been found that the stability of monoperphthalic acids or diperphthalic acids and mixtures thereof, particularly perisophthalic acid or the chloro derivatives thereof, can be substantially improved by incorporating therewith an amount of an alkali metal or alkaline earth metal salt of an acid having an ionization constant at 25 C. for the first hydrogen of at least lXl preferably not less than 1X 1 0 Anhydrous alkali metal or alkaline earth metal sulfates, such as sodium sulfate or magnesium sulfate, are especially effective for this purpose. Other sulfates which can be used include potassium sulfate (K 50 ammonium sulfate, lithium sulfate, and like sulfates of alkali metals. Bisulfates also may be used. Thus, sodium bisulfate or potassium bisulfate or like alkali metal bisulfate stabilize perphthalic acids although not as sodium sulfate or like neutral sulfates.

Various other salts of acids having the dissociation constants specified above with alkaline earth metals and alkali metals (ammonium salts being included within the term alkali metal salts" and magnesium within the term alkaline earth metals") such as sodium nitrate, magnesium nitrate, calcium nitrate and like nitrates, as well as the corresponding pyrophosphates or polyphosphates, may be used. Advantageously, the stabilizing salts should possess substantial water solubility, e.g., above 5 to grams per liter. However, less soluble salts, such as calcium sulfate or calcium or magnesium phosphates, may be used where solution of the salt is not important. Furthermore, these agents should be inert to peracids. Alkaline materials often are undesirable and impart instability. Consequently, the mixture of salt and perphthalic acid should advantageously have a pH not above 8, and preferably on the acid side, i.e., approximately the natural pH of the peracid.

The amount of stabilizing salt used normally is large, particularly when water soluble salts are used. As a general rule, amounts at least equal to one-half part by weight of alkali metal or alkaline earth metal salt per part by weight of the peracid are found satisfactory, and amounts in the range of one to 10 parts of stabilizing salt per part of the peracid are found useful. Even'larger amounts of such salt may be used, the major limit being simply that the peracid should not be so diluted as to effectively lose the value of its active oxygen content.

As a general rule, it is undesirable to incorporate other organic materials which can contaminate the product or promote instability of the perphthalic acid. Of course, other inert materials can be added. However, the incorporation of synthetic organic detergents, such as alkyl sulfates and sulfonates and the like, may be found to be disadvantageous to the stability of the ultimate product.

This difficulty may be avoided, however, by either coating or encapsulating the mixture of perphthalic acid and sodium sulfate or the detergent with a suitable inert protective coating, such as paraffin wax, polyvinyl alcohol or the solid polymeric glycols or the like, which are water soluble or water dispersible, in order to segregate the detergent, alkaline agent or like material from the perphthalic-stabilizing salt mixture. The mixture thus protected may be mixed with dry detergents or other materials, whether or not they attack unprotected perphthalic acid.

In typical examples, dry perisophthalic acid was produced according to the method described in the article in Journal of Organic Chemistry, Volume 27, page 1,336 1962) by Silbert, Siege] and Swem. The products obtained were finely divided solids which had active oxygen contents stoichiometrically equivalent to the theoretical active oxygen content of to percent diperisophthalic acid.

EXAMPLE I Average percent Percent improve- Additive Decomposition/day ment in stability None 8.6

Na SO, 0.2 4,300 new, 0.7 1.130 Na,co,, Na,so, 0.8 930 Calculated as ercent ofthe total active oxygen lost per day.

EXAMPLE ll Another sample of diperisophthalic acid was divided into four beakers. The peracid samples in three of the beakers were mixed with equal weights of solid, pulverulent sodium nitrate, ammonium sulfate and magnesium sulfate under the conditions specified in example I, and allowed to stand. Analysis after 45 days gave the following results:

Average percent Percent Improve Additive Decomposilon/day' men! in stability None 7.9

NaNO 0.9 780 mnmso, 0.6 1,220 MgSQ. 0.5 1,480

Calculated as percent of total active oxygen lost per day.

EXAMPLE III A third sample of diperisophthalic acid was divided into two portions, and one portion was mixed with an equal weight of finely powdered sodium sulfate. Both the diluted and undiluted peracids were allowed to stand under an air atmosphere of less than 5 percent relative humidity at 60 C. for 35 days. Analysis at the end of this time indicated that the undiluted peracid decomposed at an average rate of 1.6 percent per day, and the sample of peracid which was diluted with sodium sulfate decomposed at an average rate of 0.1 percent per day.

EXAMPLE IV Attempts to stabilize other peracids, both aromatic and aliphatic, with this method have met with, at best, only a slight improvement in stability. Diperazelaic acid was mixed with three times its weight of sodium sulfate and allowed to stand at less than S-percent relative humidity and 40 C. for 70 days. A portion of the undiluted peracid was treated identically. p- Nitroperbenzoic acid was also mixed with three times its weight of sodium sulfate, and p-chloroperbenzoic acid and mchloroperbenzoic acid were both mixed with an equal weight of sodium sulfate. Each sample was allowed to stand along with an undiluted sample of the same peracid at 60 C. under a relative humidity of less than percent in the first two cases and 52 percent in the latter case. Analysis after 13-40 days indicated that the additive in some cases actually accelerated the decomposition rate of the peracid as shown in the following table:

Percent Percent Samples of diperisophthalic acid were mixed with potassium bisulfate, sodium dihydrogen phosphate and sodium tripolyphosphate and allowed to stand at 60 C. under an atmosphere of less than S-percent relative humidity for 45 days along with a sample of the undiluted peracid. The results are summarized in the following table:

Average percent Percent improve- Additive Decomposition/day ment in stability None 7.8

KHSO 2.0 290 Sodium dibasic- 0.9 990 phosphate Sodium tripoly- 0.9 990 hosphate The resulting composition is useful as a bleaching agent for the bleaching of textiles. For example, it can be used effectively in domestic washing machines as a bleaching agent which is used in conjunction with the usual detergents. It is readily soluble (particularly when water-soluble salts are used as stabilizers) and when added to the laundry solution, liberates its oxygen in a form which effectively promotes bleaching. The material can be used in conjunction with the various conventional detergents, including alkali metal silicates, synthetic organic detergents, such as sodium dodecyl sulfate or like alkali metal, alkyl or aralkyl sulfates or sulfonates, and the like.

Especially effective bleaching of textiles may be accomplished, for example, in domestic washing machines, by the use of compositions herein described as illustrated by the following:

EXAMPLE VI (7 Sta. removal (final reflectance-initial reflectance) o l (reflectance of unstained clothinitial reflectance) Washing was perfonned in a top loading home laundry machine (General Electric) using Corpus Christi city water,

using washer settings of a hot wash (49-5 1 C.), warm rinse, normal speed, i to 6 pound loading 16 gallons of water) and a l2-minute wash cycle. After filling the washer with water, 86.4 grams (one cup) of a commercial detergent (Tide) was added and the solution agitated for 15 seconds. Then the bleaching agent in an amount suflicient to give the active oxygen content specified in the ensuing table was added. Following a further 15 second agitation period, half of a 4.5-pound load of soiled clothing, the stained swatches (20 in all) and the Percent stain removal Active oxygen (parts per million) Tea stain 25 35 50 Peracid alone 40 35 45 Peracid-MgSO, mixture 70 65 65 Tide alone l9 l9 19 Coffee Stain 35 50 Peracid alone 80 PeracidMgSO, mixture I05 Tide alone 55 55 Wine Stain 35 50 Peracid alone 90 90 Peracid-MgSO, mixture l 10 Tide along 65 65 Grape Stain 35 50 Peracid alone 90 90 Peracid-MgSO, mixture 100 I07 Tide alone 7 3 73 lncrease in Reflectance (Averaging the blue. green, and amber filters) EMPA stain 35 50 Peracid alone 3 5 Peracicl-MgSO mixture l3 I2 Tide alone about 2 about 2 As the foregoing demonstrates, bleaching of textiles in aqueous media to which perphthalic acid and a magnesium salt such as magnesium sulfate have been added provides a high degree of stain removal, a level of removal which is markedly higher than when the magnesium salt is not added. Other of the hereinbefore described magnesium salts, notably the water soluble magnesium salts also provide bleaching compositions of corresponding usefulness. Besides the particular textile, percale cotton goods employed in the bleaching of example VI, other textiles (dyed and undyed) may be bleached effectively by such procedure with such compositions including other celluloses, synthetic (rayons) or natural, as well as textiles containing nylon, synthetic fiber-forming polymers including polyester types such as fortrel, Kodel and Dacron, polyacrylonitrile types such as Acrylon and Lycra;

proteinaceous materials, especially woolens and various combinations thereof.

Considerable latitude in the amount of the perphthalic acid bleaching agent and magnesium salt added to the aqueous media to form useful bleaching baths and achieve bleaching is permissible, note the benefits reaped at the varying active oxygen levels in example VI. Also bleaching is effected in an aqueous medium at all normal temperatures, usually from tap water temperatures (about 20 or 25 C.) up to about boiling, 100 C., with a range of 40 to 70 C. being recommended.

Mostly, the aqueous medium in which bleaching (including stain removal) is effected is at a slightly alkaline pH, i.e., above pH 7, typically between pH 8 and 10.

Moreover, this bleaching can and often is accomplished in aqueous medium which also includes conventional detergents.

Although the present invention has been described with reference to the specific details of certain embodiments, it is not intended that such details shall be regarded as limitations upon the scope of the invention herein described except insofar as much limitations are included in the accompanying claims.

I claim:

1. A method of bleaching which comprises forming an aqueous bleaching bath by adding both diperisophthalic acid and water-soluble magnesium salt to an aqueous medium and contacting material to be bleached with the bath.

2. The method of claim 1 wherein the salt is magnesium sulfate.

3. In the method of washing textiles in aqueous media with detergents, the improvement which comprises adding both diperisophthalic acid and water soluble magnesium salt to the aqueous media whereby to bleach the textile during the washmg.

4. The method of claim 3 wherein the magnesium salt is magnesium sulfate.

5. A method of employing diperisophthalic acid to remove stain from textiles which comprises enhancing the stainremoving effectiveness of diperisophthalic acid by contacting stained textile with an aqueous medium containing added water-soluble magnesium salt in addition to added diperisophthalic acid whereby to attain a level of stain W W removal higher than when magnesium salt is not added.

6. The method of claim 5 wherein the stained textile contacted with said aqueous medium is stained cotton textile.

7. The method of claim 5 wherein the magnesium salt is magnesium sulfate. 

2. The method of claim 1 wherein the salt is magnesium sulfate.
 3. In the method of washing textiles in aqueous media with detergents, the improvement which comprises adding both diperisophthalic acid and water soluble magnesium salt to the aqueous media whereby to bleach the textile during the washing.
 4. The method of claim 3 wherein the magnesium salt is magnesium sulfate.
 5. A method of employing diperisophthalic acid to remove stain from textiles which comprises enhancing the stain-removing effectiveness of diperisophthalic acid by contacting stained textile with an aqueous medium containing added water-soluble magnesium salt in addition to added diperisophthalic acid whereby to attain a level of stain removal higher than when magnesium salt is not added.
 6. The method of claim 5 wherein the stained textile contacted with said aqueous medium is stained cotton textile.
 7. The method of claim 5 wherein the magnesium salt is magnesium sulfate. 